J Orthop Sci (2007) 12:14–21
DOI 10.1007/s00776-006-1087-9

Original article
Validation of the Japanese Society for Surgery of the Hand version of
the Carpal Tunnel Syndrome Instrument
Toshihiko Imaeda1, Shigeharu Uchiyama2, Satoshi Toh3, Takuro Wada4, Shuji Okinaga5, Takuya Sawaizumi6,
Jun Nishida7, Koichi Kusunose8, and Shohei Omokawa9 for the Clinical Outcomes Committee of the Japanese
Orthopaedic Association and the Impairment Evaluation Committee of the Japanese Society for Surgery of
the Hand1

Department of Public Health, Fujita Health University School of Medicine, 1-98 Dengakugakubo, Kutsukakecho, Toyoake, Aichi 470-1192,
Japan
2
Department of Orthopaedic Surgery, Shinshu University School of Medicine, Matsumoto, Japan3
Department of Orthopaedic Surgery, Hirosaki University School of Medicine, Hirosaki, Japan
4
Department of Orthopaedic Surgery, School of Medicine, Sapporo Medical University, Sapporo, Japan
5
Department of Orthopaedic Surgery, Tokyo Teishin Hospital, Tokyo, Japan
6
Department of Orthopaedic Surgery, Nippon Medical School, Tokyo, Japan
7
Department of Orthopaedic Surgery, Iwate Medical University, Morioka, Japan
8
Department of Orthopaedic Surgery, Tokyo Rosai Hospital, Tokyo, Japan
9
Department of Orthopaedic Surgery, Ishin-kai Yao General Hospital, Yao, Japan

Abstract
Background. The Carpal Tunnel Syndrome Instrument(CTSI) is a disease-specific, self-administered questionnairethat consists of a symptom severity scale (SS) and a functional
status scale (FS). The CTSI was cross-culturally adapted anddeveloped by the Impairment Evaluation Committee, Japanese Society for Surgery of the Hand (JSSH). The purpose ofthis study was to test the reliability, validity, and responsiveness of the Japanese version of the CTSI (CTSI-JSSH).
Methods. A consecutive series of 87 patients with carpal tunnel syndrome completed the CTSI-JSSH, the JSSH version of
the Disability of the Arm, Shoulder, and Hand questionnaire(DASH-JSSH), and the 36-Item Short-Form Health Survey(SF-36). Seventy-two of the patients were reassessed for test–
retest reliability 1 or 2 weeks later. Reliability was investigatedby the reproducibility and the internal consistency. To analyze
the validity, a factor analysis (principal axis factoring) of the
CTSI-JSSH and the correlation coefficients between the
CTSI-JSSH and DASH-JSSH were obtained. The responsiveness was examined by calculating the standardized responsemean (SRM; mean change/SD) and effect size (mean change/
SD of baseline value) after carpal tunnel release in 42
patients.
Results. Cronbach’s alpha coefficients for the CTSI-JSSH-SS
and the CTSI-JSSH-FS were 0.84 and 0.90, respectively, andthe intraclass correlation coefficients were 0.82 and 0.83, respectively. The unidimensionality of the CTSI-JSSH-SS wasbarely confirmed; the unidimensionality of the CTSI-JSSH-FS
was confirmed. The correlation coefficients between the CTSIJSSH-FS and the CTSI-JSSH-SS or DASH-JSSH were 0.58
and 0.80, respectively. The correlation coefficient between the
CTSI-JSSH-SS and DASH-JSSH was 0.54. The correlation

Offprint requests to: T. Imaeda
Received: July 19, 2006 / Accepted: October 17, 2006

coefficients between the subscales of SF-36 and the CTSIJSSH-SS or the CTSI-JSSH-FS ranged from −0.23 to −0.66
and from −0.19 to −0.63, respectively. The SRMs/effectsizes of the CTSI-JSSH-SS and the CTSI-JSSH-FS were−0.85/−0.99 and −0.70/−0.61, which indicated that they weremore than moderately sensitive.
Conclusions. The CTSI-JSSH has sufficient reliability, validity, and responsiveness to assess the health status in carpal
tunnel syndrome.

Introduction
Health measurement scales are important patient outcome tools to measure health status and to evaluate
medical intervention.1 Recently, several measures forthe evaluation of upper extremity function have beendeveloped.2–5 Some of them are joint-specific measures2,3or region-specific measures.4,5 Others are intended toevaluate the symptoms and function of the upper extremity using disease-specific measures.6 Among theregion-specific measures, the Disability of the Arm,
Shoulder and Hand (DASH) questionnaire5 and its
short version (QuickDASH)7 are the most recently devised scales and now are widely used in several countries, including Japan, Sweden, France, Germany, Spain,
the Netherlands, Italy, and China.8–16 As one of thedisease-specific measures, a self-administered questionnaire for the assessment of severity of symptoms andfunctional status in carpal tunnel syndrome was originally devised by Levine et al.6 This instrument has beencalled by several names, e.g., the Carpal Tunnel Syndrome Instrument (CTSI),17 Brigham and Women’s

T. Imaeda et al.: Validation of the JSSH version of the CTSI

15

Carpal Tunnel Questionnaire,18 and the Boston Carpal
Tunnel Syndrome Questionnaire.19 We adopted the
CTSI for the current study. The CTSI is now available
in a few languages and has been used in several countries (e.g., Sweden,17 Spain,13 Italy,20 and the Netherlands21). The only studies of reliability and validity of
the CTSI that have been published are for the originalCTSI6 and for the Swedish version.17
We, the Impairment Evaluation Committee of theJapanese Society for Surgery of the Hand (JSSH), havecompleted cross-cultural adaptation and have developed the JSSH version of the CTSI (CTSI-JSSH).22 The
purpose of this study was to test the reliability, validity,
and responsiveness of the CTSI-JSSH and to make the
CTSI-JSSH available for use in Japan.

with the original CTSI, we developed the CTSI-JSSH(prefinal version 2). Then we commenced the pilot test.
After analyzing the pilot test data, we modified prefinal
version 2 of the CTSI-JSSH into a final version. The
final CTSI-JSSH version22 was then evaluated withregard to reliability, validity, and responsiveness.

Materials and methods
In accordance with published guidelines,23 we set up the
CTSI-JSSH committee and recruited translators, researchers, a methodologist, and a Japanese language
expert, and culturally adapted the CTSI into Japanese,
as had been done for DASH-JSSH.8
The adaptation process
The English version of the CTSI6 was translated into
Japanese by two translators whose first language wasJapanese. One of them had no medical background andthe other did have a medical background. Their two“forward” translations were synthesized into one version after being reviewed and discussed by the committee. This Japanese version (the prefinal version) wastranslated back into English by two other translators
whose first language was English. One of them wasblinded to the concepts being investigated and had no
medical background; the other had a medical background. After we compared these two back-translations
Table 1. Symptom severity scale of the Carpal Tunnel Syndrome Instrument
Item code
SS-1
SS-2
SS-3
SS-4
SS-5
SS-6
SS-7
SS-8
SS-9
SS-10
SS-11

The CTSI questionnaire
The CTSI questionnaire developed by Levine et al.6
contains two subscales: a symptom severity scale (CTSISS) (Table 1) and a functional status scale (CTSI-FS)(Table 2).
The CTSI-SS consists of eleven items which were
derived from six clinical domains for carpal tunnel syndrome: pain (three items, numbers 3–5), paresthesia(one item, number 8), numbness (one item, number 6),
weakness (one item, number 7), nocturnal symptoms(four items, numbers 1,2,9,10), and overall functional
status (one item, number 11). The eleven questions
have multiple-choice responses, scored from 1 point (nosymptom) to 5 points (most severe symptom). The overall symptom severity score is calculated as the mean of
the scores for the eleven individual items.
The CTSI-FS consists of eight functional activities
commonly affected by carpal tunnel syndrome. The
answers are rated from 1 point (no difficulty with theactivity) to 5 points (cannot perform the activity at all).
The overall score for functional status is calculated as
the mean of all eight items.
Patients and setting
The study was conducted on a consecutive series of 87
patients (15 men, 66 women) with a clinical diagnosis of
carpal tunnel syndrome seen on an outpatient or inpatient basis in five orthopedic surgery departments inJapan. The mean age was 58.3 years (SD 13.8 years,
range 21–86 years). After informed consent was obtained from the patients to participate in this study, theyanswered the CTSI-JSSH questionnaire,22 the JSSH
version of the DASH (DASH-JSSH) questionnaire,8Scale item
Severity of nocturnal pain
Frequency of nocturnal awakening due to pain
Severity of daytime pain
Frequency of daytime pain
Duration of daytime pain
Severity of numbness
Severity of weakness
Severity of tingling
Severity of nocturnal numbness or tingling
Frequency of nocturnal awakening due tonumbness or tingling
Difficulty with grasping and use of small objects

Table 2. Functional status scale of the Carpal Tunnel Syndrome Instrument
Item code
FS-1
FS-2
FS-3
FS-4
FS-5
FS-6
FS-7
FS-8

Scale item
Writing
Buttoning clothes
Holding a book while reading
Gripping the telephone receiver
Opening jars
Performing household chores
Carrying of grocery bags
Bathing and dressing

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T. Imaeda et al.: Validation of the JSSH version of the CTSI

the official Japanese version of the 36-Item Short-Form
Health Survey (SF-36, version 1.2),24 and the Visual
Analog Scale (VAS) (0–10 scale) for pain. The datacollected from the 87 patients were used as a baseline
value. Among the 87 patients, the 72 who had received
no treatment such as medication or rehabilitation during the consecutive visits were readministered the CTSIJSSH questionnaire 1 or 2 weeks later. The 45 patients
who underwent carpal tunnel release answered the
CTSI-JSSH and the DASH-JSSH questionnaires twice,once preoperatively and once postoperatively, 3 months
after surgery. The protocol of this study was reviewed
and approved by the institutional review boards prior
to implementation.

CTSI-JSSH-FS, DASH-JSSH, SF-36-BP, age) werenormally distributed and the other interval measurements (SF-36-PF, SF-36-RP, VAS for pain, and timerequired to fill out the questionnaire of the CTSI-JSSH)
were not normally distributed. Then Cronbach’s alphawas used to assess internal consistency of the CTSIJSSH (SS and FS). The instrument test–retest reliabilityof CTSI-JSSH (SS and FS) was assessed with the intraclass correlation coefficient (ICC). All correlation coefficients among the CTSI-JSSH, DASH-JSSH, andSF-36 results were calculated with use of Spearman’srank correlation coefficient. The changes in measurements after carpal tunnel release were assessed with aparametric test (paired t test). All statistical analyses
were conducted using the Statistical Package for Social
Science (SPSS) version 14.0J software (SPSS Japan,
Tokyo). The critical values for significance were set at
P < 0.05.

Assessment of reliability, validity, and responsiveness
Reliability was investigated by looking at the reproducibility and internal consistency based on the test–retest
method. The following analyses were conducted to examine the validity. A factor analysis (principal axis factoring) was conducted to examine the construct validity
and the unidimensionality of the CTSI-JSSH-SS andCTSI-JSSH-FS. The completeness of item responses for
the CTSI-JSSH was examined.
Correlation coefficients between the CTSI-JSSH (SSand FS) and DASH-JSSH were obtained, and the following hypotheses were examined to investigate concurrent validity: (1) the CTSI-JSSH-SS would exhibit amoderate association with DASH-JSSH; (2) the CTSIJSSH-FS would exhibit the strongest association with
DASH-JSSH.
Correlation coefficients between the CTSI and SF-36
were also obtained, and the following hypotheses were
examined to investigate concurrent validity: (1) the
CTSI-JSSH-SS would exhibit the strongest association
with “bodily pain” (SF-36-BP) among the SF-36 subscales; (2) the CTSI-JSSH-FS would exhibit the strongest association with “physical functioning” (SF-36-PF)
or “role-physical” (SF-36-RP). These three subscales of
SF-36 were chosen because the correlation between
DASH-JSSH and the three subscales of SF-36 was morethan moderate.8
The responsiveness of both the CTSI-JSSH andDASH-JSSH were examined by calculating the standardized response mean (SRM; mean change/SD)25 andthe effect size (mean change/SD of baseline value)26
after carpal tunnel release.

Results
Completeness of item responses
No patients had difficulty completing the CTSI-JSSH
questionnaire. It took them 5 min 40 s, on average, tofinish the questionnaire (median: 5 min, range: 2–30 min).
Most of the patients considered all the items of the CTSI
to be clear. Nine of the 72 patients (nonrespondentgroup) did not answer one or more items of the CTSI.
Two of these patients failed to answer more than two
items, with each leaving four items unanswered. Items
5, 7, and 8 of the CTSI-JSSH-SS were left unansweredby one patient each. Three patients did not answer items
1 and 3 of the CTSI-JSSH-FS. Two patients did not respond to item 7 of the CTSI-JSSH-FS. Items 2, 4, 6, and
8 of CTSI-JSSH-FS were each unanswered by one patient. The mean age [70 ± 12 (SD) years] of the nonrespondent group (n = 9) was significantly larger than themean age (57 ± 13 years) of the respondent group (n =78) who completed all the items (P = 0.008).
The mean, median, SD, and range of the CTSI-JSSH,
DASH-JSSH, SF-36, and VAS for pain scores are shownin Table 3. The number of ceiling scores in the CTSIJSSH were identified. One and five patients had theminimum disability score of zero (ceiling) on the CTSIJSSH-SS and the CTSI-JSSH-FS, respectively. No patient had a maximum disability score of 5 (floor) either
on the CTSI-JSSH-SS or on the CTSI-JSSH-FS.

Statistical analysis
The distributions of the CTSI-JSSH, DASH-JSSH, SF36, VAS for pain, the ages of the subjects, and the timerequired to fill out the CTSI-JSSH questionnaire wereassessed. The interval measurements (CTSI-JSSH-SS,

Reliability
Internal consistency was assessed by use of Cronbach’s
alpha coefficient. The alpha coefficient for the 11 itemsin the CTSI-JSSH-SS was 0.839 (n = 84). When the al-

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17

Table 3. Mean scores and range of scores for CTSI, DASH, SF-36, and VAS
Instrument scale (n)

Mean

SD

MedianMinimum

Maximum

CTSI-JSSH-SS (87)
CTSI-JSSH-FS (87)
DASH-JSSH (79)
SF-36-PF (77)SF-36-RP (66)
SF-36-BP (77)
VAS (77)

2.53
2.20
31.2
65.2
56.6
44.9
3.4

0.72
0.80
18.3
29.2
40.2
19.9
3.0

2.54
2.00
27.5
75.0
75.0
41.0
3.0

1.00a
1.00a
0a
0b
0b
0b
0a

4.27
4.00
74.1
100a
100a
100a
10b

CTSI-JSSH-SS, the symptom severity scale of the Japanese Society for Surgery of the Hand
version of the Carpal Tunnel Syndrome Instrument (CTSI-JSSH); CTSI-JSSH-FS, the functional
status scale of the CTSI-JSSH; DASH-JSSH, the disability/symptom scale of the Japaneseversion of the Disability of the Arm, Shoulder, and Hand questionnaire; SF-36-PF, physicalfunctioning subscale of the 36-Item Short-Form Health Survey (SF-36); SF-36-RP, role-physicalsubscale of SF-36; SF-36-BP, bodily pain subscale of SF-36; VAS, Visual Analog Scale for pain
(0–10 scale)a
Maximum health status scores (ceiling)b
Minimum health status scores (floor)pha coefficient was calculated for each of the 11 items
by eliminating each item, one by one, the range was
0.814–0.838; no item was found to change the internalconsistency substantially. The alpha coefficient for the
8 items of the CTSI-JSSH-FS was 0.900 (n = 82). Whenthe alpha coefficient was calculated for each of the 8
items by eliminating each item, one by one, the range
was 0.879–0.900; no item was found to change the internal consistency substantially.
Instrument test–retest reliability was assessed with
the intraclass correlation coefficient (ICC). There were72 patients involved in the assessment of test–retest reliability, and the period between the first and second tests
was on average 10.7 days (SD 6.0 days). The ICCs for
the CTSI-JSSH-SS and the CTSI-JSSH-FS were 0.82
(95%CI: 0.79–0.89) and 0.83 (95%CI: 0.74–0.89), respectively. Both ICCs for the CTSI-JSSH subscales
indicate sufficient reproducibility.

Fig. 1. Scree plot of the factors in the symptom severity scaleof the Japanese Society for Surgery of the Hand version of
the Carpal Tunnel Syndrome Instrument (CTSI-JSSH)

Validity
A factor analysis (principal axis factoring) was conducted to confirm the unidimensionality of the CTSIJSSH-SS and the CTSI-JSSH-FS. The first factor of the
CTSI-JSSH-SS had an eigenvalue (amount of variationin the total sample accounted for by that factor)14 of
4.44, which explained 40% of the total variance of the
CTSI-JSSH-SS scores of the patients (Fig. 1). The second factor of the CTSI-JSSH-SS had an eigenvalue of
1.86, which explained 17% of the total variance of the
CTSI-JSSH-SS scores of the patients, these two factors
thus explain 57% of the cumulative variance of the
CTSI-JSSH-SS scores of the patients (Fig. 1). Factor
analysis indicated the presence of at least two factors
in the CTSI-JSSH-SS, which means bidimensionality.
Next, further factor analysis (principal axis factoring set
for two factors, rotation: promax) was conducted. Whenlooking at the first factor loading for each item, someitems (items 1, 2, 6, 9, 10, and 11) had a loading (thecorrelation with the total score) of 0.4 or higher (Table4). When looking at the second factor loading for each
item, some items (items 3, 4, and 5) had a loading of 0.4
or higher (Table 4). When we adopted one factor to
conduct factor analysis (principal axis factoring) of the
CTSI-JSSH-SS, the loading of all factors was more than0.4, except for item 11.
The first factor of the CTSI-JSSH-FS had an eigenvalue of 4.79, which explained 60% of the total varianceof the CTSI-JSSH-FS scores of the patients (Fig. 2). The
unidimensionality of the CTSI-JSSH-FS was found to
be strong as a result of the low eigenvalue of the second

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T. Imaeda et al.: Validation of the JSSH version of the CTSI

Table 4. Pattern matrix (rotated, promax) of factor analysis
for CTSI-SS
Component
Item

1

CTSI-SS-2
CTSI-SS-9
CTSI-SS-10
CTSI-SS-6
CTSI-SS-1
CTSI-SS-11
CTSI-SS-7
CTSI-SS-8
CTSI-SS-4
CTSI-SS-5
CTSI-SS-3

0.827
0.805
0.795
0.607
0.542
0.415
0.319
0.271

2

0.324
0.204
0.222
1.042
0.771
0.746

Loadings of more than 0.2 are shown in this table
Bold figures indicate values greater than 0.4

Fig. 2. Scree plot of the factors in the functional status scaleof CTSI-JSSH

Table 5. CTSI, DASH, SF-36, VAS and their correlation
Correlationa with
Instrument scale (n)CTSI-JSSH-SS (87)

CTSI-JSSH-FS

DASH-JSSH

CTSI-JSSH-FS (87)
DASH-JSSH (79)
SF-36-PF (77)SF-36-RP (66)
SF-36-BP (77)
VAS (77)

0.58**
0.54**−0.23−0.29*−0.66**
0.40**—
0.80**−0.19−0.50**−0.63**
0.23*——−0.34**−0.71**−0.68**
0.32*** P < 0.05** P < 0.01aSpearman’s rank correlation

factor (0.96, Fig. 2). When looking at the first factor
loading for each item, all items had a loading of 0.4 orhigher.
The correlation coefficients between the CTSI-JSSHSS and the CTSI-JSSH-FS or the DASH-JSSH were0.58 and 0.54, respectively (Table 5, P < 0.01). These
results indicate a moderate correlation between the
CTSI-JSSH-SS and the CTSI-JSSH-FS, and between
the CTSI-JSSH-SS and DASH-JSSH. The correlation
coefficient between the CTSI-JSSH-FS and DASHJSSH was 0.80 (Table 5, P < 0.01), which indicates astrong correlation between them. These results support
the hypotheses set down in advance.
The correlations between the CTSI-JSSH-SS score
and the subscales of the SF-36 scale ranged from −0.23
to −0.66 (Table 5). The strongest correlation was observed for “bodily pain.” The correlation between the
CTSI-JSSH-SS and “role-physical” or “physical functioning” were somewhat weak. These results support
the hypotheses set down in advance.

The correlations between the CTSI-JSSH-FS score
and the subscales of the SF-36 scale ranged from −0.19
to −0.63 (Table 5). The strongest correlation was observed for “bodily pain” followed by “role-physical.”
The correlation between the CTSI-JSSH-FS and “physical functioning” was somewhat weak. These results
contradicted the hypotheses set down in advance, except for “role-physical.”No statistical difference (P = 0.904) in age was foundbetween men [mean (SD): 60 (12) years] and women[mean (SD): 59 (13) years]. The CTSI-JSSH-SS scoresfor men [mean (SD): 2.68 (0.80)] and women [mean(SD): 2.49 (0.68)] were compared by Student’s t test.
There was no statistical difference between them
(P = 0.29). The CTSI-JSSH-FS scores for men [mean(SD): 2.40 (0.80)] and women [mean (SD): 2.21 (0.74)]
were similarly compared and there was no statisticaldifference between them (P = 0.37). These results support our hypothesis. The correlation between age andthe CTSI-JSSH-SS or the CTSI-JSSH-FS score was

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19

weak (r = −0.041, P = 0.704; r = 0.014, P = 0.898,
respectively).
The correlation between the CTSI-JSSH-SS scoreand VAS for pain was moderate but the correlation
between the CTSI-JSSH-FS score and VAS for pain
was weak (Table 5).

As for measurement precision, recommended reliability standards for individual-level applications range
from a low of 0.90 to a high of 0.95, which is the desired
standard.27 Most general health status measures [e.g.,
SF-36, the Nottingham Health Profile (NHP), and the
Functional Status Questionnaire (FSQ)],27 as well as
lesion- or joint-specific questionnaires [e.g., the RolandMorris Disability Questionnaire28 and the Western
Ontario and McMaster Universities osteoarthritis
index (WOMAC)] cannot meet this standard, whether
they are designed for individual patient applications orgroup-level applications. Most translated DASH versions8,10,12–15 as well as the original DASH29 have internalconsistency values higher than 0.95 and meet this standard. But the symptom severity scale and functional
status scale of the CTSI-JSSH had internal consistency
values of 0.84 and 0.90. We would thus prefer that the
CTSI-JSSH be used for groups of patients or workers.
There are many types of validation processes of quality of life (QOL) questionnaires. The present study adopted correlation between CTSI-JSSH and other QOL
questionnaires such as SF-36 and DASH. Although
Levine et al.6 and Atroshi et al.17 did not demonstrate
those correlations, Gay et al.30 studied the correlation
between the original DASH and the original CTSI 6
weeks after carpal tunnel release. The correlation
coefficients between the CTSI-SS and the CTSI-FS orDASH were 0.74 and 0.88 respectively.30 The validation
process of the CTSI-JSSH questionnaire has shown thatit has lower validity than the original CTSI.30 The strong
correlations between the CTSI-JSSH and DASH-JSSH
support the validity of CTSI-JSSH (Table 5). The moderate correlations between the CTSI-JSSH and SF-36
subscales (physical functioning and bodily pain) also
support this validity. These results demonstrate that the
CTSI-JSSH measures the important elements that makeup health-related QOL.
Another validation method is factor analysis, which
was not adopted in other validation studies of the
CTSI.6,17 The symptom severity scale of the CTSI-JSSH
exhibited bidimensionality (Table 4, Fig. 1). The two
factors could be identified from this table. The second
factor is “daytime pain” (items 3–5). The first factor isother symptoms such as nocturnal symptoms (items 1,
2, 9, 10), numbness (item 6), weakness (item 7), paresthesia (item 8), and overall functional status (item 11).
Atroshi et al.17 divided the symptom severity scale into
two components: the pain component (items 1–5) andthe sensory component (items 6 and 8–11), and successfully demonstrated that the responsiveness of the sensory component is larger than that of the pain component,
although they did not conduct a factor analysis. Theoretically, overall functional status (item 11 of symptom
severity) could be included in the functional status scale.
These results show that the symptom severity scale of

ResponsivenessForty-two patients of the 45 who underwent carpal tunnel release completed the CTSI-JSSH and the DASHJSSH questionnaires at 3 months (mean: 96 days, SD: 9days) after the surgery. The mean subject age was 62
years (SD: 14 years, range: 21–86 years). There were 5
men and 37 women. The calculated standardized response mean (SRM) and effect size for CTSI-JSSH-SS(n = 42), CTSI-JSSH-FS (n = 42), and DASH-JSSH (n= 40) was −0.85/−0.99, −0.70/−0.61, and −0.35/−0.36, respectively. There were statistical differences between
the mean value of preoperative and postoperative
CTSI-JSSH-SS scores (P < 0.001), CTSI-JSSH-FS scores(P < 0.001), and DASH-JSSH scores (P = 0.034).

Discussion
Adaptation of the CTSI questionnaire for Japanese patients was performed following a systematic standardized approach.23 The purpose of this study was to
examine the psychometric qualities of the CTSI by assessing its psychometric standards in the areas of reliability, validity, and responsiveness.
The CTSI consists of an 11-item symptom severity
scale and an 8-item functional status scale. It took patients a shorter time to complete the CTSI-JSSH compared with the time to complete the DASH-JSSH.8 This
indicated that the questionnaire was easy to understand.
Most older patients left no more than two items unanswered and those were thought to be pertaining to specific activities that those individuals did not perform.
The lack of floor effects assures the authors of the validity of both subscales of the CTSI-JSSH.
As for internal consistency, the Cronbach’s alpha coefficients for CTSI-JSSH-SS (0.83) and CTSI-JSSH-FS(0.90) were equivalent to those of the original versionof the CTSI (SS: 0.89, FS: 0.91)6 and those of the Swedish version of the CTSI (SS: 0.80, FS: 0.87).17 As for reproducibility, the ICC of the CTSI-JSSH-SS (0.82) andthe CTSI-JSSH-FS (0.83) were not equivalent to thePearson correlation coefficients of the original versionof the CTSI (SS: 0.91, FS: 0.93)6 but were equivalent to
the Pearson correlation coefficients of the Swedish version of the CTSI (SS: 0.80, FS: 0.87).17 Therefore theresults for the internal consistency and reproducibilityof the CTSI-JSSH indicate sufficient reliability.

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T. Imaeda et al.: Validation of the JSSH version of the CTSI

the CTSI-JSSH could be divided into two. If we adopt
one factor for the symptom severity scale of the CTSIJSSH, it barely maintains unidimensionality from theresults of factor loading. This means that the symptom
severity scale of the CTSI-JSSH has a high quality ofvalidation.
The functional status scale of the CTSI-JSSH exhibited high unidimensionality and there was no low itemscale correlation. The loading of this scale was veryhigh. These results show that the functional status scaleof the CTSI-JSSH has a high quality of validation.
Cohen’s rule of thumb for interpreting the “effect size
index” (i.e., a value of 0.2 is small, 0.5 is moderate, and
0.8 or greater is large) can be applied to the SRM.25 The
responsiveness of the symptom severity scale and functional status scale of the CTSI-JSSH for patients withcarpal tunnel syndrome was large and moderate, respectively, 3 months after carpal tunnel release operation, although other studies of the CTSI17,30 showed
twice the responsiveness levels of our results. The responsiveness levels of both subscales of CTSI-JSSH
were twice that of DASH-JSSH. Gay et al.30 also described similar findings. Moreover, there were statisticaldifferences between the mean value of preoperativeand postoperative subscale scores for the CTSI-JSSH.
We believe that the strengths of this study are that
the CTSI-JSSH demonstrated good reproducibility,
consistency, and validity. Moreover, it had at least moderate responsiveness. A limitation of the present study
is that we could not successfully demonstrate the responsiveness of the CTSI-JSSH because the sample size
was relatively small and the patients’ response rate waslow. Moreover, the subjects of this study are not representative of the general population.

4. Martin DP, Engelberg R, Agel J, Swiontrowski MF. Comparisonof the Musculoskeletal Function Assessment questionnaire with
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8. Imaeda T, Toh S, Nakao Y, Nishida J, Hirata H, Ijichi M, et al.
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Surgery of the Hand. Validation of the Japanese Society for Surgery of the Hand version of the Disability of the Arm, Shoulder,and Hand questionnaire. J Orthop Sci 2005;10:353–9.
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Orthop Sci 2006;11:248–53.
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A. The disabilities of the arm, shoulder and hand (DASH)
outcome questionnaire: reliability and validity of the Swedish
version evaluated in 176 patients. Acta Orthop Scand 2000;71:
613–8.
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DASH. Adaptation française d’un outil d’évaluation international. Chir Main 2001;20:294–302 (in French).
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questionnaire (DASH-G). J Rheumatol 2002;29:401–2.
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the Spanish version of the DASH and carpal tunnel syndrome
health-related quality-of-life instruments: cross-cultural adaptation process and reliability. J Hand Surg [Am] 2002;27:334–43.
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AH, van Meeteren NLU. Psychometric qualities of the Dutch
language version of the Disabilities of the Arm, Shoulder, andHand questionnaire (DASH-DLV). J Hand Ther 2002;15:347–
54.
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PC, et al. Italian version of the Disability of the Arm, Shoulder
and Hand (DASH) questionnaire. Cross-cultural adaptation andvalidation. J Hand Surg [Br] 2003;28:179–86.
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Conclusions
We can conclude that the Japanese Society for Surgeryof the Hand version of the Carpal Tunnel Syndrome
Instrument (CTSI-JSSH) has sufficient reliability, validity, and responsiveness to assess the severity of symptoms and the functional status in carpal tunnel syndrome.
Above all, the CTSI-JSSH can be used for groups ofpatients.
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